Assist transportation method and its device

ABSTRACT

To provide an assist transportation device capable of properly communicating a reaction force to a worker due to contact without damaging any product and obstacle even if the product contacts the obstacle under work. The assist transportation device for reducing a load applied to the worker when the worker operates transportation means to transport an instrument panel P includes instrument panel holding means  27  for holding the instrument panel P, floating mechanism  30  set to the connection portion between the instrument panel holding means  27  and the transportation means, displacement sensor  61  for detecting the displacement value of the floating mechanism  30 , and position instruction computing portion  62  for computing the displacement value detected by the displacement sensor  61  to calculate a reaction force, in which the reaction force is transferred to the worker operating the transportation means.

TECHNICAL FIELD

The present invention relates to an assist transportation method and itsdevice for decreasing the load to a worker when the worker operatestransportation means to transport a product.

BACKGROUND ART

Conventionally, known is a work assist to which impedance control isapplied by which a worker can perform transportation work while theworker feels as if he/she transports a light weight object though aheavy one. The work assist is a power assist provided with first toeighth movable bodies for supporting a heavy object, actuators formoving the movable bodies, and a controller for controlling outputs ofthe actuators, detecting a force to be indirectly applied to the heavyobject by a worker by a force sensor in order to transport the heavyobject fixed to the eighth movable body by worker's way, controlling thefirst to eighth movable bodies in accordance with the information, andreducing the load to the worker (for example, refer to Japanese PatentLaid-Open No. 2000-84881).

However in the case of the work assist disclosed in Japanese PatentLaid-Open No. 2000-84881, while a worker transports a heavy object orwhen the worker positions and sets the heavy object to a settingportion, even if the heavy object contacts with an obstacle, a reactionforce generated in the heavy object due to the contact is not conductedto a worker operating the assist. Therefore, there is a problem that theworker cannot detect that the heavy object contacts with the obstacleand thereby continues transportation work, and the heavy object or theheavy-object setting portion may be damaged.

The present invention is made to solve the above problem of aconventional technique and its object is to provide an assisttransportation method and a device capable of properly communicating areaction force due to contact to a worker without damaging a product andan obstacle even if the product contacts with an obstacle at the time ofwork.

DISCLOSURE OF THE INVENTION

To solve the above problem, the invention of claim 1 is an assisttransportation method for reducing a load applied to a worker when theworker operates transportation means to transport a product, in whichwhen the product contacts with an obstacle, the product is floated fromthe transportation means to moderate the impact, the displacement valueof the product due to floating is detected, the displacement value isprocessed to compute a reaction force due to the impact, and thereaction force is communicated to the worker.

According to the invention, when the product contacts with the obstacle,the impact is moderated by setting a floating mechanism between thetransportation means and the product and the displacement value of thefloating mechanism is processed to compute an impact force, and thereaction force by the impact force is communicated to the worker throughthe transportation means. Therefore, when the worker transports theproduct or sets the product to a component to be set, the worker canefficiently perform work while the worker feels that the worker contactswith any obstacle or component to be set without damaging a product orthe component to be set even if the product contacts with any obstacleor component to be set.

The invention of claim 2 is an assist transportation device for reducinga load applied to a worker when the worker operates transportation meansto transport a product, which includes holding means for holding aproduct, a floating mechanism set to the connection portion between theholding means and the transportation means, displacement detection meansfor detecting the displacement value of the floating mechanism, andcontrol means for processing the displacement value detected by thedisplacement detection means and computing a reaction force, andcommunicates the reaction force to the worker operating thetransportation means.

According to the invention, because the floating mechanism set betweenthe holding means for holding a product and the transportation means,displacement detection means for detecting the displacement value of thefloating mechanism, and control means for processing the displacementvalue detected by the displacement detection means and computing areaction force are included, even if the product contacts with anyobstacle or component to be set when the worker transports the productor sets the product to the component to be set, the product or thecomponent to be set cannot be damaged. Moreover, the worker canefficiently perform work while feeling that the worker contacts with theobstacle or component to be set.

The invention of claim 3 is an assist transportation method for reducinga load applied to a worker when the worker operates transportation meansto transport a product, in which a work area through which a product canfreely move is set and a limit area formed adjacently to the work areafor generating a predetermined reaction force so as to return a productto the work area when the product comes in is set.

According to the invention, because the work area through which aproduct can freely move is set and the limit area for generating apredetermined reaction force so as to return the product to the workarea when the product comes in is set, the worker can efficientlyperform the transportation work without being aware of an obstacle orwithout applying an impact to the product.

The invention of claim 4 is an assist transportation device for reducinga load applied to a worker when the worker operates transportation meansto transport a product, which includes a work area through which theproduct can freely move, a limit area formed adjacently to the work areato generate a predetermined reaction force so as to return the productto the work area when the product comes in, and control means forprocessing the incoming value of the product incoming to the limit areato compute the reaction force.

According to the invention, because the word area through which theproduct can freely move, limit area formed adjacently to the work areato generate a predetermined reaction force so as to return the productto the work area when the product comes in, and control means forprocessing the incoming value of the product entering the limit area tocompute the reaction force are included, the worker can efficientlyperform transportation work without being aware of an obstacle orwithout applying an impact to the product.

The invention of claim 5 is an assist transportation method for reducinga load applied to a worker when the worker operates transportation meansto transport a product, in which the product is floated from thetransportation means, the displacement value of the product due tofloating is detected when the worker holds the product and operates itin a direction for transporting the product, the displacement value isprocessed, and the product is assist-transported as a target value ofthe transportation means.

The invention of claim 6 is an assist transportation device for reducinga load applied to a worker when the worker operates transportation meansto transport a product, which includes holding means for holding theproduct, operation handle set to the holding means for the worker tolead the product in a desired direction, floating mechanism set to theconnection portion between the holding means and the transportationmeans, displacement detection means for detecting the displacement valueof the floating mechanism, and control means for processing thedisplacement value detected by the displacement detection means toassist-transport the product as a target value of the transportationmeans.

According to inventions of claims 5 and 6, it is possible to efficientlyreduce a load applied to a worker while keeping a state havingpreferable operability without directly feeling driving oftransportation means. Moreover, when a worker transports a product orsets the product to a component to be set, a load applied to the workeris reduced and even if the product contacts with any obstacle orcomponent to be set, the product or component to be set is not damaged.Moreover, the worker can efficiently perform work while feeling that theproduct contacts with any obstacle or component to be set.

The invention of claim 7 is an assist transportation method for reducinga load applied to a worker who operates an operation handle set totransportation means to transport a product, in which the direction andmagnitude of an operation force applied to the operation handle when theworker operates the product in a direction for transporting the productare detected, the direction and magnitude of an external force when theproduct contacts with an obstacle, directions and magnitudes of theoperation force and the external force are processed to assist-transportthe product as a target value of the transportation means, and thereaction force by the external force is communicated to the worker.

The invention of claim 8 is an assist transportation device for reducinga load applied to a worker for operating an operation handle set totransportation means to transport a product, in which holding means forholding the product, operation force detection means for detecting thedirection and magnitude of an operation force applied to the operationhandle set to the connection portion between the holding means and thetransportation means, external force detection means set to theconnection portion between the holding means and the transportationmeans to detect the direction and the magnitude of an external forceapplied to the holding means, and control means for processing thedirection and magnitude of the operation force detected by the operationforce detection means and the direction and magnitude of the externalforce detected by the external force detection means andassist-transporting the product as a target value of the transportationmeans are included and the reaction force by the external force iscommunicated to the worker.

According to inventions of claims 7 and 8, it is possible to efficientlyreduce a load applied to a worker while keeping a state of preferableoperability without directly feeling driving of transportation means.Moreover, when a worker transports a product or sets the product to acomponent to be set, a load applied to the worker is reduced and theproduct or component to be set is not damaged even if the productcontacts with any obstacle or component to be set. Furthermore, theworker can efficiently perform work while feeling that the productcontacts with any obstacle or component to be set.

The invention of claim 9 is an assist transportation method for reducinga load applied to a worker for operating transportation means totransport a product, in which the direction and magnitude of anoperation force when the worker holds the product and moves thetransportation means in a direction for transporting the product aredetected and the direction and magnitude of the operation force isprocessed to assist-transport the product as a target value of thetransportation means.

The invention of claim 10 is an assist transportation device forreducing a load applied to worker for operating transportation means totransport a product, which includes holding means for holding theproduct, an operation handle set to the holding means to lead theproduct in a direction desired by the worker, external force detectionmeans set to the connection portion between the holding means and thetransportation means to detect the direction and magnitude of anexternal force applied to the holding means, and control means forprocessing the direction and magnitude of the external force detected bythe external force detection means to assist-transport the product as atarget value of the transportation means.

According to inventions of claims 9 and 10, it is possible toefficiently reduce a load applied to a worker while keeping a state ofpreferable operability without directly feeling driving of thetransportation means. Moreover, when a worker transports a product orsets the product to a component to be set, a load applied to the workeris reduced and even if the product contacts with any obstacle orcomponent to be set, the product or component to be set is not damaged.Furthermore, the worker can efficiently perform work while feeling thatthe product contacts with any obstacle or component to be set.

The invention of claim 11 is an assist transportation method forreducing a load applied to a worker when the worker operatestransportation means to transport a product, which comprises a conditionsetting step of setting a transportation area and assist condition everypredetermined position of a transportation route and a transportationarea setting step of setting a transportation area between adjacentpredetermined positions and an assist condition through operations inaccordance with the transportation area and the assist condition everypredetermined position set in the condition setting step to set thetransportation area of components.

According to the invention, because a transportation area and an assistcondition every predetermined position of a transportation route and atransportation area and an assist condition are automatically set overthe whole transportation route connecting predetermined positions, it ispossible to easily set the transportation area. Therefore, it ispossible to efficiently correspond to change of assist conditions due tochange of transportation routes and change of transportation components.

The invention of claim 12 is an assist transportation method forreducing a load applied to a worker when the worker operatestransportation means to transport a product, which comprises atransportation area confirmation step of confirming a transportationroute and a transportation area in accordance with position data for aplurality of teaching points and transportation area data set everyteaching point, a transportation-portion position confirmation step ofobtaining the position of a transportation portion for supporting aproduct, and a transportation-portion-position moving step of obtaininga transportation route closest to the position of the transportationportion and moving the transportation portion to the predeterminedposition of the obtained transportation route or into transportationarea of the obtained transportation route when the position of thetransportation portion is out of the transportation area, wherein thetransportation portion is returned into the transportation area when theposition of the transportation portion for supporting a product is outof the transportation area.

According to the invention, when a transportation portion is out of atransportation area, it is possible to automatically move the positionof the transportation portion onto the nearest transportation route orinto the transportation area of the nearest transportation route.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic illustration of an instrument-panel settingstation to which a first embodiment using an assist transportationmethod and its device of the present invention is applied;

FIGS. 2(a) and 2(b) are schematic diagrams of a floating mechanism, inwhich FIG. 2(a) is a perspective view of the floating mechanism and FIG.2(b) is a schematic view showing the inside of the floating mechanism;

FIG. 3 is a block diagram of a control system for power assist controlin the first embodiment using the assist transportation method and itsdevice of the present invention;

FIG. 4 is a conceptual illustration of a reaction-power detectioncontrol in the first embodiment;

FIGS. 5 to 7 are illustrations of a work area setting method;

FIG. 8 is a schematic illustration of an instrument-panel settingstation to which a second embodiment of an assist transportation methodand its device of the present invention is applied;

FIG. 9 is a block diagram of a control system for power assist controlin the second embodiment of the assist transportation method and itsdevice of the present invention;

FIG. 10 is a conceptual illustration of an assist transportation controlin the second embodiment;

FIG. 11 is a general schematic diagram of a vehicle-door assembly lineto which an assist transportation method and its device of the presentinvention are applied;

FIG. 12 is a perspective view of transportation means;

FIG. 13 is a top view of the machine pedestal of transportation means;

FIG. 14 is a perspective view of the connection portion betweentransportation means and holding means;

FIG. 15 is an illustration of holding means;

FIG. 16 is a block diagram of a control system for power assist controlof a third embodiment of an assist transportation method and its deviceof the present invention;

FIG. 17 is a conceptual illustration of an assist transportation controlin the third embodiment;

FIG. 18 is an illustration of a door viewed from an inner panel side;

FIGS. 19(a) and 19(b) are illustrations of a door-glass elevatingregulator, in which FIG. 19(a) is a back view of the regulator and FIG.19(b) is an illustration viewed from the surface side;

FIGS. 20(a) and 20(b) are illustrations of a state of setting adoor-glass elevating regulator in a door inner panel, in which FIG.20(a) is a state diagram when inserting a door-glass elevating regulatorinto the opening of an inner panel and FIG. 20(b) is state diagram whenthe door-glass elevating regulator is rotated and fixed to the innerpanel after inserting the regulator;

FIG. 21 is a perspective view of the connection portion betweentransportation means and holding means;

FIG. 22 is a block diagram of a control system for power assist controlin a fourth embodiment of an assist transportation method and its deviceof the present invention;

FIG. 23 is a conceptual illustration of assist transportation control inthe fourth embodiment;

FIG. 24 is a block diagram of a fifth embodiment of an assisttransportation method and its device of the present invention;

FIG. 25 is an illustration showing a teaching job program;

FIG. 26 is an illustration showing an assist parameter table;

FIG. 27 is an illustration showing an assist area setting method;

FIG. 28 is an illustration showing the switching characteristic ofassist impedance;

FIGS. 29(a) and 29(b) are illustrations of the relating processingbetween the present position and an assist area;

FIG. 30 is an illustration (1) of computation processing of assist areaand assist impedance when the assist area and assist impedance arechanged between teaching points;

FIG. 31 is an illustration (2) of computation processing of assist areaand assist impedance when the assist area and assist impedance arechanged between teaching points; and

FIG. 32 is an illustration of computation of the returning force of aninvisible wall and switching processing of assist impedance,

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiments of the present invention are described below by referring tothe accompanying drawings.

At the instrument panel setting station of a vehicle assembly line,vehicle bodies Wa positioned to a mounting jig set on a slat conveyerare continuously transported at equal speed in the direction of thearrow A as shown in FIG. 1.

A first embodiment using an assist transportation method and its deviceof the present invention is constituted as described below. In FIG. 1,an assist transportation device shows two states, that is, a position(original position) for horizontally (Y direction) holding an instrumentpanel P of the vehicle body Wa and a position of setting the instrumentpanel P to the vehicle body Wa.

A first frame body 1 is set above the vehicle assembly line in parallelwith (X direction) the vehicle assembly line. Two slide rails 2 and onerack 3 are set to the first frame body 1 in parallel with the vehicleassembly line. A plurality of rollers 4 are rotatably engaged with thetwo slide rails 2 and a pinion gear 6 set to a motor 5 is engaged withthe rack 3. The rollers 4 and motor 5 are set to a support member 7. Themotor 5 is a motor for synchronizing the assist transportation devicewith the vehicle body Wa.

Moreover, a second frame body 8 is connected to the rollers 4 and thesupport member 7 of the motor 5. Two slide rails 9 and one rack 10 areset to the second frame body 8 orthogonally to the vehicle assemblyline. A plurality of rollers 11 are rotatably engaged with the two sliderails 9 and a pinion gear 13 set to a motor 12 is engaged with the rack10. The rollers 11 and motor 12 are set to a support member 14. Themotor 12 is a motor for power-assist-driving the assist transportationdevice in Y-axis direction.

Moreover, a third frame body 15 is connected to the rollers 11 and thesupport member 14 of the motor 12. Two slide rails 16 and one rack 17are set to the third frame body 15 in parallel with the vehicle assemblyline. A plurality of slide guides are slidably engaged with the twoslide rails 16 and a pinion gear 20 set to the motor 19 is engaged withthe rack 17. The slide guides and motor 19 are set to lower-facemarginal portion of a table 21. The motor 19 is a motor forpower-assist-driving the assist transportation device in X-axisdirection.

Furthermore, a telescopit-type slide guide 22 is set to the lower-facecenter of the table 21, a feed screw (not illustrated) is set in theslide guide 22, and a motor 23 is connected to the feed screw. The motor23 is vertically set to the table 21. The motor 23 is a motor forpower-assist-driving the assist transportation device vertically (Zdirection).

A cylindrical arm 24 is extended to the side facing the vehicle body Wanearby the lower end of the slide guide 22 and a box 25 housing afloating mechanism is set to the front end of the arm 24. Instrumentpanel holding means 27 for holding the instrument panel P is set to theface of the box 25 facing the traveling direction of the vehicle body Wathrough the floating mechanism and an operation handle 28 is set to theface of the box 25 facing the vehicle body Wa.

As shown in FIG. 2, a floating mechanism 30 is provided with a fixedtable 32 in which a pair of slide rails 31 are set horizontally (Ydirection) to the front end of the vehicle body Wa, a first slide table34 in which a slide guide 33 slidably engaged with the slide rails 31 isset to the rear face, and a second slide table 37 in which a slide guide36 slidably engaged with a pair of slide rails 35 vertically (Zdirection) set to the vehicle body Wa at the front end of the firstslide table 34 is set to the rear face.

A centering member 38 to be held is set to the front center of the fixedtable 32 and a pair of centering cylinders 39 in which the front end ofa piston rod are faced to the horizontal direction (Y direction) of thevehicle body Wa in a state capable of holding the centering member 38 tobe held is set to the rear face of the first slide table 34. Adisplacement sensor is built in the centering cylinder 39 and thereby itis possible to always confirm a displacement value in the horizontaldirection (Y direction) of the vehicle body Wa of the first slide table34.

Moreover, a centering member 40 to be held is set to the front center ofthe first slide table 34 and a pair of centering cylinders 41 in whichthe front end of a piston rod is faced in the vertical direction (Zdirection) of the vehicle body Wa in a sate capable of holding thecentering member 40 to be held are set to the rear face of the secondslide table 37. A displacement sensor is built in the centering cylinder41 and thereby it is possible to always confirm a displacement value inthe vertical direction (Z direction) of the vehicle body Wa of thesecond slide table 37.

Moreover, a cylinder 42 directing the front end of a piston rod in thetraveling direction of the vehicle body Wa is set to the front of thesecond slide table 37 and a pair of slide guides 43 are set in parallelwith the cylinder 42. A rectangular parallelepiped block 44 is fixed tothe front end of the piston rod of the cylinder 42 and the front end ofthe slide guide 43 and an arm 45 for connecting the instrument panelholding means 27 is set to the front of the block 44. A displacementsensor is built in the cylinder 42 and thereby it is possible to alwaysconfirm a displacement value in the cross-direction (X direction) of thevehicle body Wa of the block 44.

As shown in FIG. 1, the instrument panel holding means 27 is constitutedof a base pedestal 47 set to the front end of the arm 45 through aconnection member 46 by directing the longitudinal direction to thehorizontal direction (Y direction) of the vehicle body Wa, a pair ofslide rails 48 set to both ends of the front of the base pedestal 47 inthe horizontal direction (Y direction) of the vehicle body Wa, a pair ofslide tables 50 set to a slide guide 49 slidably engaged with the sliderails 48, a pair of support arms 52 having a plurality of connectionpins 51 set to the slide tables 50, and a pair of cylinders 53 forsliding the support arms 52 toward the reference hole 26 of theinstrument panel P.

Moreover, load cells (force sensors) for detecting forces in orthogonalthree-axis directions are built in the setting portion of the operationhandle 28 of the box 25 supporting the instrument panel holding means 27to always detect forces applied to the horizontal direction (Ydirection) of the vehicle body Wa, cross direction (X direction) of thevehicle body Wa, and vertical direction (Z direction) of the vehiclebody Wa. Forces detected by these force sensors are used forpower-assist control of this device.

Displacement values detected by displacement sensors built in thecylinders 39, 41, and 42 of the floating mechanism 30 are used togenerate a reaction force when the instrument panel P held by theinstrument panel holding means 27 contacts with the vehicle body Wa oran obstacle.

As shown in FIG. 3, a control system for power assist control in thefirst embodiment using an assist transportation method and its device isconstituted of a force sensor 60 for detecting forces in orthogonalthree-axis directions set to the setting portion of the operation handle28, displacement sensor 61 for detecting displacement values inorthogonal three axis directions set to the floating mechanism 30,position instruction computing portion 62, position control portion 63,motor (for Y axis) 12, motor (for X axis) 19, and motor (for Z axis) 23serving as assist driving actuators, and position and speed detectionmeans 64 for detecting positions and speeds of the motors 12, 19, and23.

The information on forces applied to the horizontal direction (Ydirection) of the vehicle body Wa, cross direction (X direction) of thevehicle body Wa, and vertical direction (z direction) of the vehiclebody Wa detected by the force sensor 60 are input to the positioninstruction computing portion 62. The position instruction computingportion 62 computes assist-driving data F for the motor (for Y axis) 12,motor (for X axis) 19, and motor (for Z axis) 23 to perform assistdriving in accordance with the force information and inputs the data Fto the position control portion 63.

The position control portion 63 performs control so that the motor (forY axis) 12, motor (for X axis) 19, and motor (for Z axis) 23 performassist driving in accordance with the assist driving data F. In thiscase, positions and speeds of the motor (for Y axis) 12, motor (for Xaxis) 19, and motor (for Z axis) 23 are detected by the position andspeed detection means 64 and fed back to the position instructioncomputing portion 62 and position control portion 63.

Moreover, as shown in FIG. 4, when the instrument panel P held by theinstrument panel holding means 27 contacts with the vehicle body Wa oran obstacle, at least one of three displacement sensors 61 set to thefloating mechanism 30 detects a displacement value x and thedisplacement value x is input to the position instruction computingportion 62. FIG. 4 shows one axis (X axis) and it is assumed that theX-axis cylinder 42 of the floating mechanism 30 for connecting theinstrument panel holding means 27 with the arm 24 of the assisttransportation device has the same characteristic as a spring.

The position instruction computing portion 62 computes reaction-forcegeneration data f in accordance with the information on the displacementvalue x. In this case, by assuming f=K·x, it is possible to createrigidity feeling as a spring constant in which K can be set to anoptional value. Therefore, as the displacement value x increases, aworker feels a larger reaction force. It is possible to use not only thedisplacement value x but also the speed and acceleration to compute areaction force.

Moreover, the position instruction computing portion 62 subtracts thereaction force generation data f from the assist driving data F for themotor (for Y axis) 12, motor (for X axis) 19, and motor (for Z axis) 23to perform assist driving and inputs the instruction value of theposition computed by using the subtraction result (F-f) to the positioncontrol portion 63.

The position control portion 63 performs control so that the motor (forY axis) 12, motor (for X axis) 19, and motor (for Z axis) 23 performassist driving while generating reaction forces with the subtractionresult (F-f). In this case, positions and speeds of the motor (for Yaxis) 12, motor (for X axis) 19, and motor (for Z axis) 23 are detectedby the position and speed detection means 64 and fed back to theposition instruction computing portion 62 and the position controlportion 63.

Moreover, in the case of an assist transportation method and its deviceof the present invention, by making it possible for the assist to freelymove through a space in an operation range when operating the assist, itinterferes with the vehicle body Wa or the like. Therefore, as shown inFIG. 5, by setting not a mechanical limiter having impact feeling but alimiter for controlling a movable range in software so as to hold a workarea We in the operation range in the cross direction (X direction) ofthe vehicle body Wa, it is possible to form limit areas La and Lb in anarea exceeding the limiter. Moreover, it is possible to form a limitarea so as to hold the work area We in the operation range in thehorizontal direction (Y direction) of the vehicle body Wa and thevertical direction (Z direction) of the vehicle body Wa.

In the work area We, power assist driving according to normal impedancecontrol is performed and in the limit areas La and Lb, it is changed toimpedance control using a control expression including the expression ofrigidity characteristic (f=Kd·(x−xd), x>xd or x<−xd) is started. In thiscase, f denotes a force so that the instrument panel P returns to thework area We from the limit areas La and Lb, Kd denotes a springconstant which can be set to an optional value, x denotes the coordinatevalue at an end of a workpiece (instrument panel P), xd denotes acoordinate value of the vehicle body Wa with which an end of theworkpiece (instrument panel P) may contact, and (x−xd) denotes an entryvalue (entry distance from work area We) to the limit areas La and Lb ofthe workpiece (instrument panel P).

Moreover, because the spring constant Kd can be set to an optional valueby software, it is possible to change the value by limit areas, forexample, by the limit areas La and Lb or change the value in accordancewith the distance from the work area We in the limit areas La and Lb.

Furthermore, as shown in FIG. 6, when putting the workpiece (instrumentpanel P) into the vehicle body Wa from a front-door opening bysynchronizing the workpiece with vehicle body Wa transported by a slatconveyer and setting the workpiece to a predetermined position, it ispossible to set the workpiece so that the work area We and limit areasLa and Lb move synchronously with the vehicle body Wa. In this case itis also possible to set the work area We and limit areas La and Lb inaccordance with a coordinate system at the vehicle body Wa side.

Moreover, as shown in FIG. 7, in one cycle until the workpiece(instrument panel P) is set to the vehicle body Wa after being held, itis possible to change limit areas in accordance with an operation mode(workpiece setting preparation mode, workpiece setting mode, orin-vehicle moving mode).

For example, it is possible to set the limit areas La and Lb to bothends of the operation range in the cross direction (X direction) of thevehicle body Wa orthogonal to the traveling direction (Y direction) ofthe workpiece in the work setting preparation mode and work settingmode. Moreover, in the vehicle moving mode, it is possible to set limitareas Lc and Ld to both ends of the operation range in the horizontaldirection (Y direction) of the vehicle body Wa in which the workpiecemay contact with the vehicle body Wa and the limit area Lb to either endof the operation range in the cross direction (X direction) of thevehicle body Wa. Therefore, it is possible to move the workpiece(instrument panel P) along the limit areas La, Lb, Lc, and Ld.

Operations of the assist transportation device and the assisttransportation method of the first embodiment constituted as describedabove are described below. To hold the instrument panel P transported tothe instrument panel supply position B shown in FIG. 1, a workeroperates the operation handle 28 of the assist transportation devicestopped at the original position, opens a pair of support arms 52, andmoves the instrument panel holding means 27 up to the instrument panelsupply position B in which the instrument panel is mounted on a carriage(not illustrated).

Then, by facing the connection pin 51 to the reference hole 26 of theinstrument panel P and then driving the cylinder 53, and inserting theconnection pin 51 into the reference hole 26, the instrument panelholding means 27 holds the instrument panel P. Moreover, when raisingthe instrument panel P from the carriage and operating the operationhandle 28 in a direction for moving the instrument panel P, the motor(for Y axis) 12, motor (for X axis) 19, and motor (for Z axis) 23perform assist driving for reducing a load of a worker.

Then, by operating the operation handle 28 so that the instrument panelP moves synchronously with the vehicle body Wa, the instrument panel Pis further transported into the vehicle body Wa from the front-dooropening of the vehicle body Wa to move the panel P nearby theinstrument-panel-setting positioning pin Wp set to the vehicle body Wa.In this case, the instrument-panel-setting positioning pin Wp maycontact with a bracket on which a pin-inserting guide hole is formed oran end of the instrument panel P may contact with the vehicle body Wa ata high probability.

When the instrument panel P contacts with the vehicle body Wa, acylinder located in the direction in which the instrument panel P isreturned among the cylinders 39, 41, and 42 set to the floatingmechanism 30 is contracted and a displacement sensor built in thecylinder detects the displacement value. The motor (for Y axis) 12,motor (for X axis) 19, and motor (for Z axis) 23 are controlled so thata worker for operating the assist transportation device feels a reactionforce due to contact between the instrument panel P and the vehicle bodyWa.

According to the above assist control, the worker detects that theinstrument panel P approaches its setting position and transports theinstrument panel P to a position nearby the setting portion of thevehicle body Wa and then can perform the setting work by manuallydelicately adjusting the position of the instrument panel P. The rangeof position adjustment in this case can be absorbed by the floatingmechanism 30. Therefore, no impact is added to this device.

When the above setting work is completed and the worker brings theinstrument panel holding means 27 to the outside of the vehicle body Wa,the worker operates the operation switch for work completion. Then, theassist transportation device automatically returns to the originalposition without contacting with the vehicle body Wa or facilitiesaround a line.

Moreover, the work area We of the instrument panel holding means 27 ispreviously set by setting the limit areas La and Lb. Therefore, theworker does not make the instrument panel P contact with the vehiclebody Wa or facilities around the line while transporting the instrumentpanel P.

Moreover, even if the worker operates the operating handle 28 so as tomove the instrument panel holding means 27 from the work area We to thelimit areas La and Lb, motors 12, 19, and 23 serving as power-assistdriving actuators is controlled so that an impact does not occur and areaction force for returning the instrument panel holding means 27 tothe work area We occurs. Therefore, no impact is applied to this deviceor instrument panel P. Therefore, the worker can perform work withoutbeing aware of boundaries between the work area We and the limit areasLa and Lb.

Then, second embodiment of an assist transportation method and itsdevice of the present invention has a configuration same as theabove-described first embodiment except that a pair of operation handles28 a and 28 b are set to the instrument panel holding means 27 and acontrol system is used.

As shown in FIG. 9, a control system for power assist control in thesecond embodiment is constituted of displacement sensors 61 fordetecting displacement values in orthogonal three-axis directions set tothe floating mechanism 30, target value computing portion 65, controlportion 66, motor (for Y axis) 12, motor (for X axis) 19, motor (for Zaxis) 23 serving as assist driving actuators, and position and speeddetection means 64 for detecting positions and speeds of the motors 12,19 and 23.

As shown in FIG. 10, when a worker grips operation handles 28 a and 28 band leads the instrument panel P held by the instrument panel holingmeans 27 in a desired direction, at least one of three displacementsensors 61 set to the floating mechanism 30 detects a displacement valueand the displacement value is input to the target value computingportion 65.

Moreover, when the instrument panel P held by the instrument panelholding means 27 contacts with the vehicle body Wa or an obstacle, atleast one of three displacement sensors 61 set to the floating mechanism30 detects a displacement value and the displacement value is input tothe target value computing portion 65. FIG. 10 shows one axis (X axis)and it is assumed that the X-axis cylinder 42 of the floating mechanism30 for connecting the instrument panel holding means 27 with the arm 24of the assist transportation device has the same characteristic as aspring.

The target value computing portion 65 computes target values (targettrajectory, speed, and assist force) of an assist transportation devicein accordance with displacement values of the displacement sensors 61.For example, when it is assumed that x is a displacement value of thedisplacement sensor 61, pd is a target trajectory, Kd is a desiredspring coefficient, Dd is a desired viscous friction coefficient, and Mdis a desired mass, the following expression (1) is effected.d ² Pd/dt ²=(Kdx+Dddx/dt)/Md  (1)

For simplification, the expression is shown by only one axis (X axis).Actually, there are three axes (X, Y, and Z).

Moreover, the target value computing portion 65 computes target values(target trajectory, speed, and assist force) in accordance with theexpression (1) for the motor (for Y axis) 12, motor (for X axis) 19, andmotor (for Z axis) 23 to drive an assist in accordance with theexpression (1) and inputs the target values to the control portion 66.

The control portion 66 controls the motor (for Y axis) 12, motor (for Xaxis) 19, and motor (for Z axis) 23 so as to follow computing results(trajectory: pd, speed: dpd/dt, and acceleration: d²pd/dt²) by thetarget value computing portion 65. In this case, positions and speeds ofthe motor (for Y axis) 12, motor (for X axis) 19, and motor (for Z axis)23 are detected by the position and speed detection means 64 and fedback to the target value computing portion 65 and control portion 66.

Operations of the assist transportation device of the second embodimentconstituted as described above and an assist transportation method aredescribed below. To hold the instrument panel P transported to theinstrument panel supply position B shown in FIG. 8, a worker operatesthe operation handles 28 a and 28 b of the assist transportation devicestopped at the original position, opens a pair of support arms 52, andmounts the instrument panel P on a carriage (not illustrated), and movesthe instrument panel holding means 27 up to the instrument panel supplyposition B in which the instrument panel is mounted on a carriage (notillustrated).

Then, by directing the connection pin 51 to the reference hole 26 of theinstrument panel P and then, driving the cylinder 53, and inserting theconnection pin 51 into the reference hole 26, the instrument panelholding means 27 holds the instrument panel P. Moreover, when the workraises the instrument panel P from the carriage and operates theoperation handles 28 a and 28 b in a direction for moving the instrumentpanel P, the motor (for Y axis) 12, motor (for X axis) 19, and motor(for Z axis) 23 perform assist driving for reducing a load applied tothe worker.

Then, the operation handles 28 a and 28 b are operated so that theinstrument panel P moves synchronously with the vehicle body Wa andmoreover, the instrument panel P is transported into the vehicle body Wafrom the front-door opening portion of the vehicle body Wa and moved upto the vicinity of the instrument-panel-setting positioning pin Wp setto the vehicle body Wa. In this case, the instrument-panel-settingpositioning pin Wp may contact with a bracket on which a pin insertingguide hole of the instrument panel P is formed or an end of theinstrument panel P may contact with the vehicle body Wa at a highprobability.

When the instrument panel P contacts with the vehicle body Wa, acylinder located in the direction in which the instrument panel P isreturned among the cylinders 39, 41, and 42 set to the floatingmechanism 30 contracts and the displacement sensor 61 built in thecylinder detects the displacement value. The motor (for Y axis) 12,motor (for X axis) 19, and motor (for Z axis) 23 are controlled so thata worker operating the assist transportation device feels a reactionforce due to contact between the instrument panel P and the vehicle bodyWa in accordance with a displacement value detected by the displacementsensor 61.

In accordance with the assist control, the worker feels that theinstrument panel P approaches its setting position and transports theinstrument panel P up to the vicinity of the setting portion of thevehicle body Wa and then, can perform the setting operation by manuallyperforming delicate position adjustment. Because the range for positionadjustment can be absorbed by the floating mechanism 30, no impact isapplied to this device.

When the above setting work is completed and the worker brings theinstrument panel holding means 27 to the outside of the vehicle body Wa,the worker operates an operation switch for work end. Then, the assisttransportation device automatically returns to the original positionwithout contacting with the vehicle body Wa or circumferentialfacilities.

Then, a third embodiment of an assist transportation method and itsdevice of the present invention is applied to the door-glasselevating-regulator setting step portion of a vehicle door assembly lineso that a door-glass elevating regulator can be efficiently set to avehicle door to be pitch-fed.

That is, as shown in FIG. 11, the vehicle door assembly line 101includes a door transportation line 102 for pitch-feeding a vehicle doorW and a plurality of setting step portions 103 to be sequentiallyarranged from the upstream side to the downstream side of the doortransportation line 102 and each setting component is set to the door Wby the setting step portions 103.

Moreover, some of the setting step portions 103 are used as stepportions for setting a door-glass elevating regulator R and thetransportation means 104 shown in FIG. 12 is set to the step portion forsetting the door-glass elevating regulator R.

In the door transportation line 102, a pair of right and left doors W ofthe same vehicle is pitch-transported and the sets are aligned andvertically mounted on one rectangular pallet p (FIG. 12) while directinginner panel-Wi sides in the same direction. A plurality of pallets p areproximity-arranged along the line and at the same time the pallets p aretransported by a constant stroke and stopped for a certain period andthe above operations are repeated.

As shown in FIG. 12, the transportation means 104 includes a portalmachine pedestal 105 set so as to straddle the door transportation line102 and holding means 106 capable of moving in the multispindledirection from the machine pedestal 105 and the holding means 106 isconstituted as a setting apparatus for setting the door-glass-elevatingregulator R (FIG. 19) so that it can be moved between a component supplyposition A set nearby the machine pedestal 105 and a setting position Bof the stopped door W.

First, relevant equipment is described. A pair of upper and lower sliderails 108 is set to either side of an upper beam 107 of the machinepedestal 105 and a rack 109 is set between the slide rails 108,

Then, a slide table 112 is slidably engaged with the slide rails 108through a slide guide 111, a first motor (for X axis) 113 is set to theslide table 112 as an actuator and a pinion gear to be driven by thefirst motor 113 is protruded to the back of the slide table 112 andengaged with the rack 109. Therefore, the slide table 112 canhorizontally move by the operation of the first motor 113.

Moreover, a support table 115 is set to the surface of the slide table112 through a setting pedestal, a pair of slide guides 116 is set to thesurface of the support table 115, a second motor 117 (for Z axis) is setto the back of the support table 115 as one of actuators, the rotatingshaft of the second motor 117 protrudes to the surface side of thesupport table 115, and a pinion gear (not illustrated) is set to thefront end of the rotating shaft. Furthermore, the pinion gear gears witha rack 119 of an elevating table 118 to be described below.

The elevating table 118 includes a pair of slide rails 121 to beslidably engaged with the slide guide 116 of the support table 115 andthe rack 119 set between the slide rails 121 so that it can bevertically moved in accordance with the operation of the second motor117.

A support pedestal 122 protruding forward is set to the lower end of theelevating table 118 and a third motor 123 (for horizontal-rotational Sshaft) as a part of an actuator. Moreover, the output shaft of the thirdmotor 123 is connected to the proximal end of a horizontal arm 124horizontally protruded from the lower portion of the support pedestal122 via the gear and the horizontal arm 124 can be rotated about thevertical shaft at the proximal end side by the driving of the thirdmotor 123 as shown in FIG. 13.

By driving the first to third motors (X axis, Z axis, and x axis) 113,117, and 123, it is possible to change positions of a product(door-glass-elevating regulator R) in a three-dimensional space.

Moreover, as shown in FIG. 14, fourth to sixth motors (for rotation)125, 127, and 128 are set as some of actuators whose output shafts areorthogonal to each other. That is, the fourth motor (for rotational αaxis) 125 is vertically set to the upper face at the front end of thehorizontal arm 124, a vertical arm 126 is connected to the output shaftof the fourth motor 125, the fifth motor (for rotational α axis) 127 isset to the lower end of the vertical arm 126 through a bracket 127 a,the sixth motor (for rotational γ axis) is set to the output shaft ofthe fifth motor 127 through a bracket 128 a, and the holding means 106is set to the output shaft of the sixth motor 128 through the settingportion 129 a of an operation handle 129 and a box 130.

By driving the fourth to sixth motors (α axis, β axis, and γ axis) 125,127, and 128, it is possible to change attitudes of the product(door-glass-elevating regulator R) in a three dimensional space.

Moreover, six-axis force/torque sensors for operation inputs fordetecting the direction and magnitude of an operation force generatedwhen a worker operates the operation handle 129 are set to the settingportion 129 a of the operation handle 129 and six-axis interferencedetection force/torque sensors for detecting the direction and magnitudeof an external force when the product (door-glass-elevating regulator R)contact with an obstacle is set to the box 130. Forces detected by theseforce/torque sensors are used for power assist control of this device.

Actuators of the first to sixth motors (X axis, Z axis, S axis, α axis,β axis, and γ axis) 113, 117, 123, 125, 127, and 128 realize switchingcontrol of an automatic transportation mode which does not require aworker and an assist transportation mode capable of reducing a loadapplied to a worker though requiring the worker. Moreover, when a modechange switch is changed to the automatic transportation mode, theholding means 106 automatically moves through a previously taught route.When the automatic transportation mode is changed to the assisttransportation mode, a load applied to the worker is reduced when theworker indirectly moves the holding means 106 by the operation handle129.

Then, the holding means 106 is described below. As shown in FIG. 15, theholding means 106 has a machine pedestal table 131 connected to theoutput shaft of the sixth motor 128 through the box 130 and settingportion 129 a of the operation handle 129 and the machine pedestal table131 has a holding mechanism portion 132 for holding thedoor-glass-elevating regulator R, a positioning mechanism portion 133for positioning the door-glass-elevating regulator R to a predeterminedposition of the door W, and a fastening mechanism portion 134 forsetting the door-glass-elevating regulator R to the door W.

Moreover, the door-glass-elevating regulator R is inserted into thespace portion between an inner panel Wi and an outer panel Wo through anopening portion H of the inner panel Wi of the door W shown in FIG. 18,positioned by the positioning mechanism portion 133, and then fastenedand fixed with bolts by the fastening mechanism portion 134.

The holding mechanism portion 132 includes a first cylinder 135 set tothe front of the machine pedestal table 131, substrate 136 connected tothe front end of a cylinder rod 135 a of the first cylinder 135, motor137 set to the front of the substrate 136, and table 138 set to thefront of the rotating shaft of the motor 137. A plurality of attractionpads 141 and a bossed positioning pin 142 are set to the table 138 viaeach bracket 139 and the bossed positioning pin 142 can be inserted intothe reference hole k (FIG. 19(b)) of the door-glass-elevating regulatorR.

Moreover, a slide rail (not illustrated) is set to the side of thesubstrate 136 and slidably fitted to the slide guide 143 extended fromthe front of the machine pedestal table 131. Therefore, the substrate136 can be slid vertically to the machine pedestal table-131 face by theoperation of the first cylinder 135 and the table 138 can be rotated bya predetermined angle by the operation of the motor 137.

Furthermore, by attracting the attraction pads 141 to the surface (facein FIG. 19(b)) of the plate portion of the door-glass-elevatingregulator R while inserting the bossed positioning pin 142 into thereference hole k of the door-glass-elevating regulator R, thedoor-glass-elevating regulator R can be held and thedoor-glass-elevating regulator R is tilted to an attitude notinterfering with the margin of the opening H of the inner panel Wi andinserted by the motor 37 and then the attitude of thedoor-glass-elevating regulator R can be converted into a settingattitude.

In the case of the positioning mechanism portion 133, a support member144 is set to the front end of a support rod 147 extended from themachine pedestal table 131 through a bracket 150 and a bossed pin 145 tobe inserted into the reference hole of the inner panel and an innerpanel contact member 146 made of resin or rubber contacting with apredetermined portion of the inner panel are set to the support member144. Moreover, a pair of positioning mechanism portions 133 is usedwhile holding the holding mechanism portion 132.

Moreover, by inserting the bossed pin 145 of the positioning mechanismportion 133 into the reference hole t (FIG. 18) of the inner panel andbringing the inner-panel contact member 146 into contact with the innerpanel Wi at a predetermined position, the door W and holding means 106are aligned.

The fastening mechanism portion 134 includes a nut runner 148 slidablyengaged with a slide rail (not illustrated) formed on the side of thesupport rod 147 fixed to the machine pedestal table-131 side through aslide guide and a second cylinder 151 for advancing or retreating thenut runner 148 to or from the inner panel Wi-side. The second cylinder151 is connected to a slide-guide-provided table 149 integrated with thenut runner-148 side through a connection member 152.

Moreover, the nut runner 148 is advanced or retreated to or from theinner panel Wi in accordance with the telescopic motion of the secondcylinder 151. A pair of nut runners 148 is used. Moreover, whenpositioning the door-glass-elevating regulator R to the settingattitude, the nut runner 148 advances and the fixing operation isperformed through bolt fastening.

When a worker pushes the operation handle 129 in a direction for movingthe handle 129 while gripping a deadman switch, the automatictransportation mode is changed to the assist transportation mode so thatthe handle 129 can be transported by a small force. When the workerreleases his hand from the deadman switch, the assist transportationmode is changed to the automatic transportation mode.

As shown in FIG. 16, a control system for power assist control in thethird embodiment is constituted of six-axis operation-input force/torquesensors 160 set to the setting portion of the operation handle 128 todetect the direction and magnitude of an operation force by a workerapplied to the operation handle, six-axis interference detectionforce/torque sensors 161 set to the box 130 to detect the direction andmagnitude of an external force when the product (door-glass-elevatingregulator R) contact with an obstacle, target value computing portion162, control portion 163, position control motors (X axis, Z axis, and Saxis) 113, 117, and 123 serving as assist driving actuators, attitudecontrol motors (α axis, β axis, and γ axis) 125, 127, and 128, andposition and speed detection means 164 for detecting positions andspeeds of the motors 113, 117, 123, 125, 127, and 128.

As shown in FIG. 17, when a worker grips the operation handle 129 andleads the door-glass-elevating regulator R held by the holding means 106in a desired direction, at least one axis of six-axis operation inputforce/torque sensors 160 set to the setting portion 129 a of theoperation handle 129 detects an operation force and the operation forceis input to the target value computing portion 162.

Moreover, even if the door-glass-elevating regulator R held by theholding means 106 contacts with the door W or an obstacle, at least oneaxis of the six-axis interference detection force/torque sensors 161detects an external force and the external force is input to the targetvalue computing portion 162. FIG. 17 shows one axis (X axis).

The target value computing portion 162 computes target values (targettrajectory, speed, and assist force) of the assist transportation devicein accordance with operation forces (direction and magnitude) detectedby the operation input force/torque sensors 160 and external forces(direction and magnitude) detected by the interference detectionforce/torque sensors 161.

For example, when assuming that X-directional forces detected by theinterference detection force/torque sensor 161 is F_(x), moments aroundX axis detected by the interference detection force/torque sensors 161is Nx, X-directional forces detected by the operation input force/torquesensors 160 is f_(x), moments around X axis detected by the operationinput force/torque sensors 160 is n_(x), X-directional target trajectoryis x, target trajectory of rotation around X axis is θ, desirable massis M, desirable moment of inertia as I, desirable X-directional viscousfriction coefficient is D_(xd), and desirable viscous frictioncoefficient around X axis is D_(θd), the following expressions (2) and(3) are effected.d ² x/dt ²(f _(x) −F _(x) −D _(xd) ·dx/dt)/M  (2)d ² θ/dt ²=(n _(x) −N _(x) −D _(θd) ·dθ/dt)/I  (3)

The expressions are shown only by one axis direction (X axis direction)for simplification. In fact, expressions (2) and (3) are effected forsix axes (X axis, Z axis, S axis, α axis, β axis, and γ axis).

Moreover, the target value computing portion 162 computes target values(target trajectory, speed, and assist force) for the position controlmotors (X axis, Z axis, and S axis) 113, 117, and 123 and attitudecontrol motors (α axis, β axis, and γ axis) 125, 127, and 128 to performassist driving in accordance with the expressions (2) and (3) and inputsthe target values to the control portion 163.

The control portion 163 controls the position control motors (X axis, Zaxis, and S axis) 113, 117, and 123 and the attitude control motors (αaxis, β axis, and γ axis) 125, 127, and 128 so as to follow computingresults (trajectory: x, speed; dx/dt, and acceleration: d²x/dt²) by thetarget value computing portion 162. In this case, positions and speedsof the position control motors (X axis, Z axis, and S axis) 113, 117,and 123 and the attitude control motors (α axis, β axis, and γ axis)125, 127, and 128 are detected by the position and speed detection means164 and fed back to the target value computing portion 162 and controlportion 163.

Operations of the assist transportation device and the assisttransportation method of the third embodiment constituted as describedabove are described below.

When a pair of right and left doors W are pitch-fed along the doortransportation line 102, the door-glass-elevating regulator R isautomatically transported to the setting position B by thetransportation means 104. That is, when the holding means 106 holds thedoor-glass-elevating regulator R at the component supply position A, theregulator R is automatically transported toward a predetermined pointnearby the setting position B in accordance with a route set in theautomatic transportation mode. In this case, it is allowed to hold thedoor-glass-elevating regulator R in the automatic mode or assist mode.

When the regulator R reaches the predetermined point nearby the settingposition B, the mode of each actuator is changed to the assisttransportation mode. Therefore, when the worker pushes the operationhandle 129 in a direction for moving the handle 129 while gripping thedeadman switch of the holding means 106, the holding means 106 is movedup to the setting position B. Moreover, when the worker passes throughthe opening H of the inner panel Wi of the door W, thedoor-glass-elevating regulator R is inserted by tilting its attitude sothat the regulator R does not interfere with the margin of the opening Hby operating another switch as shown in FIG. 20(a).

Furthermore, after the worker passes through the above opening H, thebossed pin 145 of the positioning mechanism portion 133 is inserted intothe reference hole t of the inner panel Wi until the bossed portioncontacts with the surface and at the same time, positioning is performedby bringing the inner panel contact member 146 into contact with thesurface of the inner panel Wi. Thereafter, by returning the tilt of thedoor-glass-elevating regulator R and slightly moving it to the innerpanel-Wi side, the door-glass-elevating regulator R contacts with theinner panel Wi.

Then, the nut runner 148 provided with a bolt advances to the innerpanel-W1 side, the bolt is passed through the bolt hole x of the innerpanel Wi and fastened and fixed to a nut to be set to thedoor-glass-elevating regulator R. Thereby, the nut runner 148 can be setin the state shown in FIG. 20(b).

When the setting work to either of the right and left doors W iscompleted, the worker releases his hand from the deadman switch. Then,the operation mode of the holding means 106 is changed to the automaticmode and the holding means 106 automatically moves to the componentsupply position A by following a decided route. Then, the holding means106 holds the next door-glass-elevating regulator R and automaticallytransports it up to a portion nearby the setting position B inaccordance with the same procedure.

Moreover, when the holding means 106 comes up to a predetermined pointby transporting the regulator R, the present mode is changed to theassist transportation mode in accordance with the procedure same as theabove described and the regulator R is set to the other door W inaccordance with the same procedure. Then, transportation of the doortransportation line 102 is stopped until setting of the regulator R totwo doors W is completed. When setting to two doors W is completed, thenext pallet p (door W) comes through pitch transportation.

According to the above procedure, by using the holding means 106 andthereby setting the door-glass-elevating regulator R to the doors W, itis possible to very efficiently perform work and moreover, because theinner panel Wi and outer panel Wo are previously integrated, theversatility of setting of other door setting components is not impaired.

When work is performed in the automatic transportation mode and anytrouble occurs, by changing an operation switch to the assist mode, itis possible to perform transportation between all points in the assistmode. In this case, impedance setting when returning the componenttransportation means 104 to a point or area decided in the automatictransportation mode is automatically performed.

Then, as shown in FIG. 21, fourth embodiment using an assisttransportation method and its device of the present invention has thesame configuration as the third embodiment except that an operationhandle 229 is set to the holding means 106 set to the output shaft ofthe sixth motor 128 through the box 130 and a control system is used.

As shown in FIG. 22, the control system for power assist control of thefourth embodiment is constituted of six-axis interference detectionforce/torque sensors 161 set to the box 130 to detect the direction andmagnitude of an external force when the product (door-glass-elevatingregulator R) contacts with an obstacle, target value computing portion262, control portion 263, position control motors (X axis, Z axis, andsaxis) 113, 117, and 123 serving as assist driving actuators, attitudecontrol motors (α axis, β axis, and γ axis) 125, 127, and 128, andposition and speed detection means 164 for detecting positions andspeeds of the motors 113, 117, 123, 125, 127, and 128.

As shown in FIG. 23, when a worker grips the operation handle 229 andleads the door-glass-elevating regulator R held by the holding means 106in a desired direction, at least one axis of the six-axis interferencedetection force/torque sensors 161 set to the box 130 detects anoperation force and the operation force is input to the target valuecomputing portion 262.

Moreover, when the door-glass-elevating regulator R held by the holdingmeans 106 contacts with the door W or an obstacle, at least one axis ofthe six-axis interference detection force/torque sensors 161 set to thebox 130 detects an external force and the external force is input to thetarget value computing portion 262. FIG. 23 shows one axis (X axis).

The target value computing portion 262 computes target values (targettrajectory, speed, and assist force) of the assist transportation devicein accordance with operation forces and external forces detected by theinterference detection force/torque sensors 161. For example, whenassuming that the X-directional force detected by the interferencedetection force/torque sensor 161 is F_(x), the moment around X axisdetected by the interference detection force/torque sensor 161 is N_(x),X-directional target trajectory is x, target trajectory of rotationaround x axis is θ, desirable mass is M, desirable moment of inertia isI, desirable X-directional viscous friction coefficient is D_(xd), anddesirable viscous friction coefficient around X axis is D_(θd), thefollowing expressions (4) and (5) are effected.d ² x/dt ²=(−F _(x) −D _(xd) ·dx/dt)M  (4)d ² θ/dt ²=(−N _(x) −D _(θd) ·dθ/dt)/I  (5)

The expression is shown by only axis direction (X axis direction) forsimplification. In fact, the expressions (4) and (5) are effected forsix axes (X axis, Z axis, S axis, α axis, β axis, and γ axis).

Moreover, the target value computing portion 262 computes target values(target trajectory, speed, and assist force) for the position controlmotors (X axis, Z axis, and S axis) 113, 117, and 123 and attitudecontrol motors (α axis, β axis, and γ axis) 125, 127, and 128 to performassist driving in accordance with the expressions (4) and (5) and inputsthe values to the control portion 263.

The control portion 263 controls the position control motors (X axis, Zaxis, and S axis) 113, 117, and 123 and attitude control motors (α axis,β axis, and γ axis) 125, 127, and 128 so as to follow the computingresults (trajectory: x, speed: ds/dt, and acceleration: d²x/dt²) by thetarget value computing portion 262. In this case, positions and speedsof the position control motors (X axis, Z axis, and S axis) 113, 117,and 123 and attitude control motors (α axis, β axis, and γ axis) 125,127, and 128 are detected by the position and speed detection means 164and fed back to the target value computing portion 262 and controlportion 263.

Then, the fifth embodiment using an assist transportation method and itsdevice of the present invention is applied to thedoor-glass-elevating-regulator setting step portion of the vehicle doorassembly line 101 shown in FIG. 11. The vehicle door assembly line 101includes a door transportation line 102 for pitch-feeding the vehicledoor W and a plurality of setting step portions 103 to be sequentiallyarranged from the upstream side to the downstream side of the doortransportation line 102 and each setting component is set to the door Wby these setting step portions 103.

Moreover, some of the setting step portions 103 are used as a step ofsetting the door-glass-elevating regulator R and the componenttransportation apparatus (transportation means) 104 shown in FIG. 12 isset. The component transportation apparatus 104 can transport and setthe door-glass-elevating regulator R which is a component.

As shown in FIG. 24, a controller 360 is constituted of a teachingapparatus I/F (interface) portion 361, setting control portion 362, andtransportation and assist control portion 363. The controller 360 isconstituted by using a microcomputer system.

The transportation and assist control portion 363 includes an assistparameter table generating portion 364, assist parameter table 365,position computing portion 366, transportation area setting portion 367,state display portion 368, and motor driving control portion 369.

The assist parameter generating portion 364 generates the assistparameter table 365 in accordance with various commands and datasupplied from the teaching apparatus 300 through the teaching-apparatusI/F portion 361. When a remote control mode is set by the teachingapparatus 300, various commands output from the teaching apparatus 300are supplied to the motor driving control portion 369 through theteaching-apparatus I/F portion 361 and assist-parameter-table generatingportion 364. Thereby, by individually driving motors 313, 317, 323, and325 by the teaching apparatus 300, it is possible to move the holdingmeans 106 to a desired position.

The position computing portion 366 computes the present position of theholding means 106 in accordance with the position data (including angledata) detected by a first position encoder 312 for detecting theposition of the slide table 112, second position encoder 318 fordetecting the position of the support table 115, third position encoder324 for detecting the rotational position (rotation angle) of thehorizontal arm 124, and fourth position encoder 326 for detectingrotational position (rotation angle) of the vertical arm 126.

Three-dimensional present position data is supplied to theassist-parameter-table generating portion 364 and transportation areasetting portion 367. Moreover, the present position data is supplied tothe teaching apparatus 300 from the assist-parameter-table generatingportion 364 through the teaching-apparatus I/F portion 361. The teachingapparatus 300 can display the present position data on the screen of animage display unit. Moreover, the teaching apparatus 300 can set thepresent position data as a teaching-point position.

The teaching apparatus 300 can supply a previously-generated teachingjob program to the transportation and assist control portion 363 throughthe teaching-apparatus I/F portion 361.

The assist-parameter-table generating portion 364 has a nonvolatilememory for storing the teaching job program. The assist-parameter-tablegenerating portion 364 writes the teaching job program supplied from theteaching apparatus 300 in the nonvolatile memory. Theassist-parameter-table generating portion 364 updates the teaching jobprogram stored in the nonvolatile memory whenever the teaching jobprogram is supplied from the teaching apparatus 300. When power issupplied to the controller 360, the assist-parameter-table generatingportion 364 reads the teaching job program from the nonvolatile memoryand generates the assist parameter table 365.

The width W and height H of an assist area, spring coefficient AK andfriction coefficient AD of an invisible wall (virtual wall), virtualmass M, virtual friction coefficient D, reaction force coefficient HK,and reaction force friction coefficient HD are set by a teaching jobprogram for each teaching point and whether to perform automaticmovement up to the next teaching point or switch to assisttransportation is set. When automatic movement up to the next teachingpoint is performed, movement speed is set. Moreover, an audio output ofan operation guidance for a worker is set according to necessity.

FIG. 25 is an illustration showing a teaching job program. Line number0002 shows an example of setting the width W of an assist area to 200mm, the height H of the assist area to 100 mm, spring coefficient AK ofan invisible wall to 10, and friction coefficient AD of the invisiblewall to 70 by assist area setting commands. Line number 0003 shows anexample of setting virtual mass M to 10, virtual friction coefficient Dto 30, reaction force coefficient HK to 50, reaction force frictioncoefficient HD to 100 by impedance setting commands. Numerical valuesset by the assist area setting commands and assist impedance settingcommands are effective until numerical values are set by the next assistarea setting command and assist impedance setting commands. Line number0005 shows a setting example for performing automatic movement up to thenext teaching point P2 at a speed V=200 (mm/sec). Line number 0008 showsan example of outputting an audio message for prompting switching to theassist mode. Line number 0015 shows an example of setting the assistmoving speed V up to the next teaching point P4 to 30 (mm/sec).

FIG. 26 is an illustration showing an assist parameter table. Theassist-parameter-table generating portion 364 generates the assistparameter table 365 for relating teaching points to various parametersas shown in FIG. 26 by deciphering a teaching job program shown in FIG.25. The assist parameter table 365 is stored in a volatile memory suchas a RAM. Thereby, the transportation area setting portion 367 can readan assist parameter at a high speed.

FIG. 27 is an illustration showing an assist area setting method. Thetransportation area setting portion 367 sets an assist area inaccordance with the assist parameter table 365. The transportation areasetting portion 367 sets a spatial area having a width W and a height Hon a plane orthogonal to a transportation route along a transportationroute (teaching trajectory) for connecting teaching points P1 to P6 asan assist area. The assist area is set so that its center becomes thetransportation route (teaching trajectory). When the width W and heightH differ between teaching points, the width W and height H are set sothat they are slowly changed along the transportation route. FIG. 27shows a transportation route of the door-glass-elevating regulator R. Inthis case, the teaching point P1 corresponds to the component supplyposition A and the teaching point P5 corresponds to the setting positionB.

The transportation area setting portion 367 determines to which assistarea the present position (position of component to be transported) ofthe holding means 106 supplied from the position computing portion 366corresponds, computes the return force of an invisible wall, andswitches assist impedances. When the holding means 106 is moved in adirection separate from the assist area, a return force according to theinvisible-wall spring coefficient is output from the transportation areasetting portion 367.

Because the motor driving control portion 369 drives the motors 313,317, 323, and 325 so that the return force acts, the holding means 106(transportation component) is not out of the assist area. In otherwords, it is possible to move the holding means 106 only in atunnel-like transportation area comparted by the invisible wall ineither case of automatic movement and assist movement. Moreover, in thecase of this embodiment, an example of forming a rectangular assist areais shown. However, it is possible to properly set the shape of theassist area in accordance with the shape of a component to betransported or work conformation.

FIG. 28 is an illustration showing the switching characteristic of anassist impedance. In the initial stages of automatic movement and assistmovement, the virtual mass M and virtual friction coefficient D are setto small values so that a characteristic suited to transport a componentat a high speed is obtained. Moreover, the virtual mass M and virtualfriction coefficient D are maximized for setting so that acharacteristic suited to finely move components is obtained and settingfeedback can be securely obtained by increasing the reaction forcecoefficient HK and reaction-force friction coefficient HD.

FIGS. 29(a) and 29(b) are illustrations of processing for relating thepresent position with an assist area. As shown in FIG. 29(a), thetransportation area setting portion 367 searches a teaching pointclosest to the present point (present position). In this case, P(N) isselected as a shortest-distance teaching point. Then, the transportationarea setting portion 367 examines whether an intersection of aperpendicular from the present point is present in segments for twosegments P(N−1) to P(N) and P(N) to P(N+1) contacting with the shortestteaching point P(N). As shown by (case 1) in FIG. 29(b), when theintersection of the perpendicular is present in both segments, a segmentin which the distance between the intersection and the present point issmaller is selected. As shown by (case 2), when the intersection of theperpendicular is not present in both segments, a segment in which theintersection is present is selected. As shown by (case 3), when theintersection is not present in both segments, a segment in which thedistance from the intersection with a straight line obtained byextending the segment up to P (N) is smaller is selected.

FIGS. 30 and 31 are illustrations of processing for computing an assistarea and assist impedance when the assist area and assist impedance arechanged between teaching points. When the transportation area settingportion 367 selects a segment, it computes an assist area at the presentposition for the selected segment (transportation route). As shown inFIG. 30, the segment Pa to Pb is selected. When the range of the assistarea is different in one teaching point Pa and the other teaching pointPb, the range of the assist area is changed every transportationposition (present point). Therefore, it is necessary to sequentially setan assist area every present point. In FIG. 30, the width of the assistarea is set Wa and height H of it is set to Ha at one teaching point Paand the width of the assist area is set to Wb and the height of it isset to Hb at the other teaching point Pb. The distance between teachingpoints is L. Therefore, when the perpendicular intersection is presentin Pa to Pb and the distance from the teaching point Pa up to theperpendicular intersection of the present point is assumed as a, thewidth W of the assist area at that position is obtained in accordancewith the following expression (6).

Moreover, the height H of the assist area is obtained in accordance withthe following expression (7).W=Wa−(Wa−Wb)×a+L  (6)H=Ha−(Ha−Hb)×a+L  (7)

When the perpendicular intersection is present at the outside of theteaching point Pa, W is set to Wa and H is set to Ha. When theperpendicular intersection is present at the outside of the teachingpoint Pb, W is set to Wb and H is set to Hb.

The transportation area setting portion 367 similarly performcomputation for the invisible-wall spring coefficient AK andinvisible-wall friction coefficient AD. Specifically, when the springcoefficient of the teaching point Pa is set to AKa and the frictioncoefficient of it is set to ADa and the spring coefficient of theteaching point Pb is set to AKb and the friction coefficient of it isset to ADb, the spring coefficient AK at the position of the distance ais obtained in accordance with the following expression (8) and thefriction coefficient AD is obtained in accordance with the followingexpression (9).AK=AKa=(AKa−AKb)×a÷L  (8)AD=ADa−(ADa−ADb)×a÷L  (9)

As shown in FIG. 31, the virtual mass M and virtual friction coefficientD at the present point is computed and the reaction-force coefficient HKand reaction-force friction coefficient HD are computed in accordancewith the same computation method.

FIGS. 32(e) and 32(f) are illustrations of computing of return force ofan invisible wall and switching of an assist impedance. When thetransportation area setting portion 367 sets an assist area and assistimpedance for the present point, it computes the return force of aninvisible wall and switches an assist impedance in accordance with thepositional relation between the present point and the assist area. Asshown by the case 1, when the present point is present in the assistarea, the return force F is zero. As shown by the case 2, when thepresent point is protruded in the width or height direction, a returnforce corresponding to the protrusion value is computed. As shown by thecase 3, when the present point is protruded in both width and heightdirection, a return force in which a width-directional return force andheight-directional return force are synthesized is computed. Moreover,by switching an assist impedance to a value (D+AD) obtained by addinginvisible-wall friction coefficient AD to the virtual frictioncoefficient D at the outside of the assist area, the viscosity of theinvisible wall is shown.

The motor driving control portion 369 shown in FIG. 24 drives the motors313, 317, 323, and 325 so as to return the present point (position ofholding means 106, that is, transportation position of transportationcomponent) in an assist area in accordance with the return forcecomputed by the transportation area setting portion 367. Thereby, whenthe position of the holding means 106 is present out of thetransportation area in an initial state when supplying power to thetransportation means 104, it is possible to automatically return theholding means 106 to a predetermined position in the transportationarea. Moreover, after returning the position of the holding means 106into the transportation area, it is possible to move the holding means106 through a transportation route in the automatic transportation modeor assist transportation mode.

In FIG. 24, reference numeral 370 denotes a mode change switch forchanging the automatic transportation mode and assist transportationmode. Reference numeral 371 denotes a deadman switch. The deadman switch371 is a three-position switch which becomes a turned-on (close) statewhile operating a switch lever by a preferable force and becomes aturned-off (open) state in a non-operation state or when stronglygripping the switch lever. The motor driving control portion 369 stopssupply of power to the motors 313, 317, 323, and 325 and stops supply ofa work assist force (assist force) even if the mode change switch 370 isset to the assist transportation mode side when the deadman switch 371is the turned-off (open) state.

The deadman switch 371 is set to the gripping portion (assist grip) ofthe operation lever set to the machine pedestal table 131 of the holdingmeans 106. An operating force/torque sensor 372 for detecting theoperation force and operation direction by a worker is set to theoperation lever. The operating force/toque sensor 372 can use at least asensor capable of detecting operation forces in three-axis directions.Specifically, by using at least three pressure sensors and three loadcells, the operation force in each direction is detected. The motordriving control portion 369 controls work assist forces (assist forces)supplied from the motors 313, 317, 323, and 325 correspondingly toeach-directional operation force in the assist transportation mode.

A transportation component is set to the vertical arm 126 in a floatingstate through a floating mechanism. When the transportation component orthe holding mechanism portion 132 contacts with a setting portion, adisplacement occurs in the floating state and the displacement isdetected by a displacement sensor 306. The motor driving control portion369 computes a setting feedback force in accordance with thedisplacement direction, displacement value, reaction force coefficientHK, and reaction force friction coefficient HD detected by thedisplacement sensor 306 to reduce work assist forces (assist forces)supplied from the motors 313, 317 323, and 325. Thereby, the worker canfeel the setting feedback force through the operation lever.

Brake mechanisms 313A, 317A, 323A, and 325A are set to output shaftsides of the motors 313, 317, 323, and 325. These brake mechanisms 313A,317A, 323A, and 325A are respectively constituted so as to mechanicallystop the rotation of each motor. The brake mechanisms 313A, 317A, 323A,and 325A are respectively constituted so as to cancel a brake state whenpower is supplied to, for example, a solenoid.

The motor driving control portion 369 controls the brake mechanisms313A, 317A, 323A, and 325A to a brake cancel state before operating themotors 313, 317, 323, and 325. The motor driving control portion 369controls the brake mechanisms 313A, 317A, 323A, and 325A to a brakestate after a preset delay time elapses from the point of time whenstopping operations of the motors 313, 317, 323, and 325. However, inthe case of a configuration capable of detecting rotations of the motors313, 317, 323, and 325, it is allowed to control the brake mechanisms313A, 317A, 323A, and 325A to a brake state at the point of time whenrotations of the motors are stopped. Thus, it is possible to eliminatean impact when stopping component transportation.

The state display portion 368 includes various types of display unitsfor respectively displaying an operation state and alarm of thetransportation means 104 and a voice synthesizer for generating a voicemessage such as operation guide for a worker.

The setting control portion 362 controls various operations of theholding means 106. When an attraction switch 381 is operated, thesetting control portion 362 drives an attraction pump 388 to make anattraction pad 341 attract a transportation component. When an advanceswitch 382 or retreat switch 383 is operated, the setting controlportion 362 drives a first cylinder 335 to advance or retreat thesubstrate 336 of a fastening mechanism 334. When a clockwise-rotationswitch 384 or counterclockwise-rotation switch 385 is operated, thesetting control portion 362 drives a motor 337 to return the attitude ofa transportation component to a tilted state or the original state. Whena setting start switch 386 is operated, the setting control portion 362drives a second cylinder 351 and drives a nut runner 348 through a nutrunner driving portion 389 to make the nut runner 348 fasten a bolt.When a setting completion switch 387 is operated, the setting controlportion 362 completes bolt fastening work and notifies thetransportation and assist control portion 363 that setting is completed.

Then, a specific example of the operation for supplying a component inthe automatic transportation mode, setting the component in the assisttransportation mode, and returning to a component receiving position(origin) in the automatic transportation mode is described. In thiscase, it is assumed that the mode change switch 370 is set to theautomatic transportation mode side and the holding means 106 returns tothe component receiving position (origin). When the transportation andassist control portion 363 detects that a not-illustrated componentreceiving completion switch is operated, it automatically transports theholding means 106 up to the teaching point P3 through the teaching pointP2 and then stops transportation. The transportation and assist controlportion 363 generates a voice message for prompting change to the assisttransportation mode. When the mode change switch 370 is changed to theassist transportation mode side and the deadman switch 371 is turned on,the transportation and assist control portion 363 power-assists themovement of the holding means 106 in accordance with an output of theoperating force/torque sensor 372. Thereby, assist movement and assistpositioning are made and components are set.

When the transportation and assist control portion 363 receives from thesetting control portion 362 a notice showing that setting is completed,it generates a voice message for prompting change to the automaticoperation mode. When the mode change switch 370 is changed to theautomatic transportation mode side, the deadman switch 371 is turnedoff, and a not-illustrated automatic operation start switch is operated,the transportation and assist control portion 363 starts automaticmovement of the holding means 106. Thereby, the holding means 106 ismoved to the component receiving position (origin) P1 through theteaching point P6.

In the case of this embodiment, an assist area is also set to anautomatic moving route. Therefore, even if assist transportation isperformed instead of automatic transportation, it is possible totransport a component along a transportation route. Because an assistarea is narrower as approaching a component setting position, it ispossible to assist-move the component up to the vicinity of the settingposition. Moreover, because an assist impedance is increased asapproaching the component setting position, a worker can accuratelyperform positioning and setting work.

Moreover, in the case of this embodiment, even if the position of theholding means 106 is deviated from an automatic moving route, it ispossible to automatically return the holding means 106 into an automatictransportation route or transportation area (assist area).

INDUSTRIAL APPLICABILITY

According to the present invention, even if a product contacts with anyobstacle or component to be set when a worker sets a product to atransportation component or component to be set, the worker canefficiently perform the transportation work without being aware of theobstacle or applying an impact to the product.

Moreover, the worker can efficiently perform the transportation workwithout being aware of an obstacle or applying an impact to the product.

Therefore, by applying the present invention to the setting work of anautomatic production line which can be hardly fully automated, it ispossible to improve a work environment and cost performance.

1. An assist transportation method for reducing a load applied to a workwhen the worker operates transportation means to transport a product,characterized by floating the product from the transportation means whenthe product contacts with an obstacle to moderate the impact, detectingthe displacement value of the product due to floating, computing thedisplacement value to compute the reaction force due to the impact, andcommunicating the reaction force to the worker who operates thetransportation means.
 2. An assist transportation device for reducing aload applied to a worker when the worker operates transportation meansto transport a product, comprising holding means for holding theproduct, a floating mechanism set to the connection portion between theholding means and the transportation means, displacement detection meansfor detecting the displacement value of the floating mechanism, andcontrol means for computing the displacement vale detected by thedisplacement detection means and computing a reaction force,characterized by communicating the reaction force to the worker whooperates the transportation means.
 3. An assist transportation methodfor reducing a load applied to a worker when the worker operatestransportation means to transport a product, characterized by setting awork area in which the product can freely move and setting a limit areaformed adjacently to the work area to generate a predetermined reactionforce so as to return the product to the work area when the productcomes in.
 4. An assist transportation device for reducing a load appliedto a worker when the worker operates transportation means to transport aproduct, comprising a work area in which the product can freely move,and a limit area formed adjacently to the work area to generate apredetermined reaction force so as to return the product to the workarea when the product comes in, and control means for computing theentering value of the product entering the limit area and the reactionforce.
 5. An assist transportation method for reducing a load applied toa worker when the worker operates transportation means to transport aproduct, characterized by floating the product from the transportationmeans, detecting the displacement value of the product due to thefloating when the worker holds the product and operates the product in adirection for transporting the product, and computing the displacementvalue to assist-transport the product as the target value of thetransportation means.
 6. An assist transportation device for reducing aload applied to a worker when the worker operates transportation meansand transport a product, comprising holding means for holding theproduct, an operation handle set to the holding means for the worker tolead the product in a desired direction, a floating mechanism set to theconnection portion between the holding means and the transportationmeans, displacement detection means for detecting the displacement valueof the floating mechanism, and control means for computing thedisplacement value detected by the displacement detection means andassist-transporting the product as the target value of thetransportation means.
 7. An assist transportation method for reducing aload applied to a worker for operating an operation handle set totransportation means and transporting a product, characterized bydetecting the direction and magnitude of an operation force applied tothe operation handle when the worker operates the product in a directionfor transporting the product, detecting the direction and magnitude ofan external force when the product contacts with an obstacle, computingthe direction and magnitude of the external force, assist-transportingthe product as the target value of the transportation means, andcommunicating a reaction force due to the external force to the worker.8. An assist transportation device for reducing a load applied to aworker for operating an operation handle set to transportation means andtransporting a product, comprising holding means for holding theproduct, operation force detection means for detecting the direction andmagnitude of an operation force applied to the operation handle set tothe connection portion between the holding means and the transportationmeans, external force detection means set to the connection portionbetween the holding means and the transportation means to detect thedirection and magnitude of an external force applied to the holdingmeans, and control means for computing the direction and magnitude ofthe operation force detected by the operation force detection means andthe direction and magnitude of the external force detected by theexternal force detection means and assist-transporting the product asthe target value of the transportation means, characterized bycommunicating a reaction force due to the external force to the worker.9. An assist transportation method for reducing a load applied to aworker for operating transportation means and transporting a product,characterized by detecting the direction and magnitude of an operationforce when the worker grips the product and moves the transportationmeans in a direction for transporting the product, computing thedirection and magnitude of the operation force, and assist-transportingthe product as the target value of the transportation means.
 10. Anassist transportation device for reducing a load applied to a worker foroperating transportation means and transporting a product, comprisingholding means for holding the product, an operation handle set to theholding means for the worker to lead the product in a desired direction,external force detection means set to the connection portion between theholding means and the transportation means to detect the direction andmagnitude of an external force applied to the holding means, and controlmeans for computing the direction and magnitude of the external forcedetected by the external force detection means and assist-transportingthe product as the target value of the transportation means.
 11. Anassist transportation method for reducing a load applied to a workerwhen the worker operates transportation means to transport a product,comprising a condition setting step of setting a transportation area andan assist condition every predetermined position of a transportationroute and a transportation area setting step of setting a transportationarea and assist condition between predetermined positions adjacent toeach other in accordance with a transportation area and assist conditionevery predetermined position set in the condition setting step,characterized by setting the transportation area of a component.
 12. Anassist transportation method for reducing a load applied to a workerwhen the worker operates transportation means to transport a product,comprising a transportation area recognizing step of recognizing atransportation route and a transportation area in accordance with theposition data for a plurality of teaching points and transportation areadata set for each teaching point and a transportation portion positionmoving step of obtaining a transportation route closest to the positionof a transportation portion when the position of the transportationportion is out of a transportation area and moving the transportationportion into a predetermined position of the obtained transportationroute or the transportation area of the obtained transportation route,characterized by returning the transportation portion into thetransportation area when the position of the transportation portion forsupporting the product is deviated from the transportation area.